Electrode for the oxidation of nitrogen



Patented Dec. 2, 1924.

UNITED STATES PATENT OFFICE.

IBIRGER FJEIJD HALVORSEN, OE CHRISTIANIA, NORWAY, ASSIGNOR TO NOR/SK HYDRO- ELEKTRISK KVAELSTOFAKTIESELSKAIB, OF CHRISTIANIA, NORWAY.

ELECTRODE FOR THE OXIDATION OF NITROGEN.

No Drawing.

To all whom it may concern Be it known that I, BIRGER F JELD HAL-.

vonsnn, a subject of .the King of Norway, residing at Solligaten 7, Christiania, Norway, have vinvented certain new and useful Improvements in and Relating to an Electrode for the Oxidation of Nitrogen; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

When oxidizing nitrogen in electric furnaces there are no special drawbacks as far as the-electrodes are concerned, as long as they are suitably constructed and cooled. It is a difierent matter when'one wishes to increase the yieldof nitric acid either by means of using gases that are richer in oxygen than air or by using pressure that is higher than that of the atmosphere. It

-will then be perceived that the durability of the electrodes is considerably reduced on account of the increased efiiciency of the oxidation. This is, for instance, the case with materials that are most commonly used such as copper, aluminium, iron, &c. It is therefore impossible to use these materials for the making of electrodes. It is exactly the same case with electric furnaces that work under pressure. When using the so-called stainless ferro-alloys of chromenickel steel, it appears that these certainly do not become oxidized, but all the same, they last but a short time. It is evident that the terminals of the arc melt the material right through within a short time.

Application filed February 6, 1923; Serial No. 617,400.

After a great number of experiments which have been carried out by me, I have come to the conclusion that it is only possible to obtain a durable electrode when the arc foots on silver. are obtained from electrodes of pure silver, but the usual commercial silver is fully satisfactory, i. e., where the metal is mainly silver.

When carrying out comparative experiments between electrodes made of various materials (copper, aluminium, bronze, chrome-nickel-steel, &c.) and silver elec trodes in a pressure furnace at a pressure of 8-10 atm., the electrodes of the former always burned up, at the very latest, between 3-5 days, while the silver electrodes, after 2 months operation and under the same conditions, only appeared to have been burnt very little and were still perfectly serviceable.

I claim 1. In an electric furnace for the manufacture of nitrogen oxides, an electrode composed mainly of silver.

2. In an electric furnace for the manufacture of nitrogen oxides, an electrode composed of silver.

In testimony that I claim the foregoing as my invention, Ihave signed my name in presence of two subscribing witnesses.

BIRGER FJELD HALVORSEN.

WVitnesses MARIE BERGQUIST, FRIGOLF HARALDSEN.

The best results 

